Can the OPI5 be Configured to Run LCNC?

That's strange, checked it again, without the overlay I don't see ttyS2 and when I enable it I can see /dev/ttyS2. The dts 
Are you using a different dtb? Although the fiq_debugger should be default. I've no idea what else it could be. You could try with the dtb I use, the only difference I made was adding support for pwm cpu fan (with pwm overlay enabled).

It should be placed in /boot/dtb/rockchip/overlay/ and enabled in armbianEnv.txt with uart2 like you did.

No way..
it stop during boot after logo showing "(initramfs)".
Do you have "console=display" into ArmbianEnv.txt?
I tried with or without but nothing.
I replaced with your dtb but it has the same behavior.
I build the dts as other and placed in overlay folder.
Can you post your ArmbianEnv.txt please?
Then I give up.. I will use the uart0, pins should be enough.
Thanks a lot for your really precious support.

No problem, yes I still do have console=display in it, no idea what could be the cause at the moment, some difference in the kernel?

isolcpus=2,5,7 instead of 5,7 because I saw it in your cmdline, does it make a difference in latency?

I did several tests with different combinations also my side because in my case the OPI5 will be used exclusively for the CNC so I tried to give to LinuxCNC the max power I can. Adding the core 2 initially seemed better, the base-thread staid around 2,5-3us! and little bit worst the motion-thread, 1,6us instead with just 5,7 that I see 4-6us in base-thread and 1us in motion-thread.
I was looking for improving base-thread where steps are generated.
At the end performing more tests, I saw increasing up to 4-5us also with core 2.. so.. I planned to re-evaluate the core selection once the controller is driving the CNC checking for pulses with oscilloscope.
For the moment I leave also the core 2.
I know that OPI5 it has 8 cores, 4 A55 up to 1,8Ghz and 4 A76 up to 2.4GHz.. but which are the A76??  I think 4 to 8 because isolating first cores the latency is really worst but I'm not able to find this spec.
I also searched for overclocking it   but I did not found any good info about.. Unfortunately OPI5 is not so popular yet..
About serial, no way also with your ArmbianEnv, really similar than mine at the end.
I found that an issue like which I'm facing could happen if I have configured some devices that use same hardware resources.
Could be the cause?
For curiosity, could me post the list of your dev folder? Then I promise, I give up, no problem.
 

Yes cpu 0-3 A55 and cpu 4-7 A76.
4x A55 and 2x2 A76
Not sure if core 5,7 are a pair or 6,7.
To "overclock" the A76 to 2.4ghz is just simply enabling the overlay. The original filename is "rockchip-rk3588-opp-oc-24ghz.dtbo".

If you tell me which devices you've configured that might use the same resources I could try that.
 

I found an interesting thing: in dev folder I have a ttyFIQ0 that you don't have and I found that it should be the debug port!
 
Most probably the correct way is to disable it and then enable ttyS2.. or renaming it.
Could be?

That's exactly what I did with the overlay I made in Fragment@1.

Now I've disabled that overlay and it's back.
 

royka wrote:

isolcpus=2,5,7 instead of 5,7 because I saw it in your cmdline, does it make a difference in latency?

If it helps, the Odroid N2+ I played with had BIG/LITTLE cores, first 4  cores were big, last 2 little. 
Best performance was isolcpus=2,3,4,5